Fuel spray ignition atomizer nozzle

ABSTRACT

A liquid fuel spray atomizer nozzle for use with a gas turbine during combustion chamber fuel ignition, comprising a member having a high pressure air blast passageway for directing a stream of air, angularly in relation to the direction of fuel spray from a nozzle into the combustion chamber, so as to atomize and forcibly blow at least a part of the fuel toward an ignition device into ignition proximity therewith. The air blast can be blown directly across the fuel spray pattern or may be directed toward a side of the spray pattern. In all cases, the air must be under sufficient pressure to deflect and atomize the fuel spray sufficiently to provide for its ignition by the spark gap or other igniter.

De Corso et al.

[451 June 13, 1972 FUEL SPRAY IGNITION ATOMIZER NOZZLE Inventors:Serafino M. De Corso, Media; Chester A. Jersey, Wallingford, both of Pa.

Assignee: Westinghouse Electric Corporation, Pittsburgh, Pa.

Filed: Jan. 28, 1971 Appl. No.: 110,424

Int. Cl

References Cited UNITED STATES PATENTS AIR SUPPLY 3,306,333 2/1967 Mock..60/39.82 S X 2,610,092 9/1952 Thompson ..239/ 295 1,485,715 3/1924Robinson.. ....239/592 X 3,240,254 3/1966 Hughes..... ....239/102 X3,531,048 9/1970 Hughes ....239/l02 X Primary Etaminer-M. Henson Wood,.1 r. Assistant Examiner-Edwin D. Grant Attorney-A. T. Stratton, F. P.Lyle and F. Cristiano [57] ABSTRACT A liquid fuel spray atomizer nozzlefor use with a gas turbine during combustion chamber fuel ignition,comprising a member having a high pressure air blast passageway fordirecting a stream of air, angularly in relation to the direction offuel spray from a no72le into the combustion chamber, so as to atomizeand forcibly blow at least a part of the fuel toward an ignition deviceinto ignition proximity therewith. The air blast can be blown directlyacross the fuel spray pattern or may be directed toward a side of thespray pattern. In all cases, the air must be under sufficient pressureto deflect and atomize the fuel spray sufficiently to provide for itsignition by the spark gap or other igniter.

10 Claims, 4 Drawing Figures FUEL SPRAY IGNITION ATOMIZER NOZZLEBACKGROUND OF THE INVENTION This invention relates to gas turbinecombustion chamber liquid fuel supply atomization and ignition during astarting operation.

In the past, it has been found that air atomization of a liquid fuelspray assists in assuring reliable starting of gas turbine combustionchambers. This has been done by directing a plurality of air blasts withthe conventional conical liquid fuel spray pattern. The use of this typeprior system requires a costly air compressor to supply the requiredair.

SUMMARY OF THE INVENTION The present invention provides a simplifiedefficient liquid fuel spray atomizer nozzle for use in a gas turbinecombustion chamber during starting by providing a single air blaststream which is directed at a part of the fuel spray so as to deflect ittoward the igniter into igniting proximity therewith and concurrentlyatomizing it to assist the ready ignition thereof. The air blast may beblown directly across the fuel spray pattern or may be aimed to deflecta part from a side of the spray. This is conveniently done by providinga member with an air blast passageway having an orifice adjacent to thefuel spray nozzle orifice and extending angularly so as to direct theair blast in the desired direction. The air blast passageway alsopreferably is made with an initial throat which flares outwardly to theblast orifice in the form of a diverging mouth to provide for rapidexpansion of the high pressure air at the orifice and a spreading of theair blast. Further, the air preferably is supplied at a pressure highenough to provide substantially sonic air velocity at the input throat,and the mouth flare is such as to reduce the orifice pressure to about0.53 of the input pressure and result in a supersonic air velocity atthe orifice.

The limited amount of air required for this air blast can readily besupplied from a suitable storage tank of relatively small size which canbe pumped up to the needed pressure between starts by the existingconventional air compressor. It has been found that even if a separateair compressor is provided, it can be reduced in size to about an eighththat required by the prior art.

The foregoing and other advantages and features of novelty of thisinvention will be apparent from the following description referring tothe accompany drawing.

BRIEF DESCRIPTION OF THE FIGURES OF THE DRAWING In the drawing:

FIG. 1 is an axial sectional view of part of a gas turbine combustionchamber provided with one embodiment of a liquid fuel spray atomizernozzle according to this invention;

FIG. 2 is an elevational end view of another embodiment of the sprayatomizer member according to this invention;

FIG. 3 is a fragmentary sectional view along line 3-3 of the atomizingmember shown in FIG. 2; and

FIG. 4 is a fragmentary sectional view through the air blast passagewayin an atomizing member, on a fuel nozzle, showing details of the passagegeometry to provide the maximum atomizing effect.

DETAILED DESCRIPTION OF THE INVENTION Referring to the drawing, FIG. 1illustrates the upstream end of a gas turbine combustion chamber 10provided with a liquid fuel spray nozzle 11 incorporating the presentinvention. The combustion chamber is only partially shown as it maycomprise any suitable type for generating hot pressurized products ofcombustion for operating a gas turbine (not shown).

The illustrated combustion chamber 10 is of the cannister type andincludes a tubular body 12 with an upstream end wall 13 to which asuitable nozzle-mounting wall 14 is secured by suitable detachablemeans, such as bolts 15. The chamber body 12 is formed with a pluralityof axially and circumferentially spaced apertures 16 for the passage ofcompressed air into the combustion chamber from the surrounding space ina suitable conventional plenum chamber, not shown. The liquid fuel spraynozzle 11 is supplied with fuel under pressure from a suitable source,not shown, through a conduit 17 connected to a fuel inlet passage 18 ina nozzle body 19. The pressurized liquid fuel is adapted to be sprayedby the nozzle 11 into the combustion chamber in a pattern which is asubstantially hollow conical fuel spray pattern 20 at atmosphericpressure; however, since the combustion chamber is under pressure, bothwhen starting up, due to the compressed air therein, and during normaloperation, due to the additional pressure of the combustion gases formedtherein, the full wide angle conical spray pattern 20 tends to contractto a narrower conical spray angle. Any suitable fuel directing structurecan be used to provide the desired conical spray pattern, and, in FIG.1, in-

cludes a small throat 21 connected to and forming the inner end portionof the fuel passage 18 and terminates in an outwardly flaring mouth 22which defines the spraying orifice of the nozzle.

It has been found that if the liquid fuel spray is finely atomized, itwill ignite much more readily in intiating combustion in the combustionchamber. In addition, the normal spray angle pattern 20 does not sprayfuel near enough to an igniter, such as a spark plug 23, to allowignition of the fuel. According to this invention, a simplified andefficient atomizing of some of the fuel during starting and deflectingof at least a portion thereof into igniting proximity with the igniter23 is provided by directing a single air blast at very high, preferablysupersonic, velocity at a part of the fuel spray pattern 20 so as toatomize and blow it in the desired direction. In the FIG. 1 embodiment,this is conveniently done by providing a jet of high velocity airthrough an atomizing orifice 24 in a face plate 25 having an air-tightseat on the inner end of the nozzle body 19.

The desired supply of air for the atomizing air jet and a rigidair-tight assembly of the nozzle structure may readily be provided byforming the face plate 25 with a central frusto-conical seat 26 snuglyfitted over a complementary frusto-conical face 27 on the inner end ofthe nozzle body 19 around the spraying orifice 22, and providing anenclosing air supply means for rigidly securing these in air-tightrelationship. In the FIG. 1 structure, this is obtained by press fittingor otherwise suitably mounting a sleeve 28 around the nozzle body 19 andproviding an air-tight seat of this sleeve 28 with a flange 29 on thenozzle body 19. This sleeve 28 is mounted in a central aperture in themounting wall 14 and is secured in position in any suitable manner, asby bolts 30 extending through a sleeve flange 31 and the wall 14. Theface plate is drawn onto its airtight seat with the nozzle body by anenclosing cap 32. In this embodiment, the cap is formed with an inwardlyextending lip 33 which engages a complementary circumferentiallyextending flange 34 on the outer edge of the face plate 25, and has athreaded engagement 35 with the adjacent end of the sleeve 28. Thesleeve 28 is made shorter than the length of the nozzle body from theflange 29 to the conical face 27, thereby providing a space 36 betweenthe end of the sleeve 28 and the adjacent side of the face plate 25,whereby tightening of the cap 32 threaded engagement 35 on the sleeve 28draws the complete nozzle assembly into a rigid air-tight unit.

Air is supplied to the atomizing orifice 24 from a suitable source, suchas a small tank 37, through a conduit 38-39 and a control valve 40. Theconduit is connected to a passageway 41 in the sleeve 28, whichpassageway 41 opens into the space 36 between the end of the sleeve andthe face plate 25 In order to provide the desired air blast deflectionof part of the liquid fuel from the conical fuel spray pattern 20 towardthe igniter 23, the face plate 25 is formed with a passageway 42extending substantially radially therethrough and at an angle betweenthe faces thereof so as to direct an air blast from the orifice 24angularly in the general fuel spray direction directly at and across theconical fuel spray pattern 20 toward the igniter 23. This air blastoperation is controlled by the valve 40, and is made operative byopening the valve during the starting ignition of fuel in the combustionchamber, whereby part of the fuel pattern is atomized and at least apart 43 thereof is deflected to igniting proximity with the igniter 23.After the fuel has ignited, the valve 40 is closed, rendering the airblast atomizer inoperative. Thus, only a relatively small amount of airis required for a short time to provide this efiicient ignitionatomization and deflection of the fuel, and the small air storagepressure tank 37 can be pumped up between starts by the conventional aircompressor or, if need be, by a relatively small auxiliary compressor.If desired, the valve 40 may be a suitable conventional electromagnetictype valve, which may be energized to open position when the igniter 23is energized and deenergized to closed position at other times tothereby provide the desired air blast control.

FIGS. 2 and 3 illustrate another embodiment of the present invention ina modified air blast nozzle atomizer structure. Similar parts areindicated by the same reference numbers as in FIG. 1. In thisembodiment, the general nozzle structure may be the same as in FIG. 1,wherein the nozzle body 19 terminates in a frusto-conical face 27 aroundan outwardly flared mouth 22 forming the fuel spray orifice connected tothe fuel supply passage throat 21. The face plate 25 is mounted on thenozzle in the same manner as in FIG. 1 and is provided with an air blastpassageway 50 between the faces thereof so as to direct an air blastangularly in the general fuel spray direction, but instead of beingdirected across the fuel spray pattern, it has an orifice 51 directed toengage a side of the conical spray pattern, whereby the air blast willdeflect a part of the fuel spray toward the igniter 23 and concurrentlyatomize this deflected spray. In some cases, this almost tangentialspray deflection blast may be advantageous because of the pressuresinvolved or because of the relative placements of certain parts, such asthe igniter 23.

FIG. 4 illustrates another embodiment of the nozzle atomizer structurewhich may be incorporated in either the FIG. 1 or the FIGS. 2 and 3 typeatomizer face plates. Similar parts are identified by the same referencenumbers as in the other figures. The additional feature in thisembodiment over the previously described nozzles is the geometry of theatomizing passageway 59 in the face plate 25, the remainder of thestructure being the same as that previously described.

In all embodiments, it is desirable that the pressure of the air at theintake to the face plate atomizing passageway be sufficient to give theair entering the passageway about sonic velocity in order for it toproduce the desired results. The FIG. 4 passageway 59 is formed with anintake throat 60 of relatively small cross-sectional area into which theair passes at about sonic velocity under the correct pressure. Thispassageway throat opens abruptly into a diverging mouth 61 of muchlarger cross-sectional area to the atomizing air blast orifice 62, soproportioned that the rapid expansion of the air therethrough providesfor a drop of the orifice air pressure to about 0.53 of the air pressurein the input throat 60. This provides a critical pressure drop whichproduces a supersonic air velocity at the air blast orifice 62, whichhas been found to improve greatly the fuel atomizing effect of the blastand also provides a broadening of the air jet with a consequentimprovement in the efficiency of the starting ignition of the fuel.

While particular embodiments of this invention have been illustrated anddescribed, many modifications thereof will occur to those skilled in theart. It is to be understood, therefore, that the invention is not to belimited to the exact details disclosed but only as required by the priorart.

The invention claimed is:

1. Combustion apparatus for a gas turbine, comprising a combustionchamber,

a liquid fuel spray atomizer nozzle for atomizing liquid fuel sprayedinto said combustion chamber,

said spray nozzle having a body defining a spraying orifice,

said body having fuel passage means for directing the liquid fuelthrough said orifice in a substantially hollow conical spray pattern atatmospheric pressure,

a fuel ignition device, and

means for providing an air blast directed at said fuel spray patternfrom only one side thereof for atomizing at least a part of the liquidfuel forming said spray pattern and directing at least a part thereofinto igniting proximity with said ignition device.

2. Combustion apparatus as defined in claim 1 wherein said air blastmeans includes means for controlling the operation thereof.

3. Combustion apparatus as defined in claim 2 wherein said controllingmeans is operative to render said air blast means operative duringstarting ignition of fuel in the combustion chamber and for rendering itotherwise inoperative.

4. Combustion apparatus as defined in claim 1 wherein said air blastmeans comprises a member having therein an air passageway with a blastorifice and constructed and arranged to direct an air blast to engage atleast a part of said fuel spray pattern and to atomize the same anddeflect at least a part of the atomized spray toward said ignitiondevice into igniting proximity therewith.

5. Combustion apparatus as defined in claim 4 wherein said air blastpassageway is constructed and arranged to direct an air blast directlyat and across the conical fuel spray pattern toward said ignitiondevice.

6. Combustion apparatus as defined in claim 4 wherein said air blastpassageway orifice is closely adjacent to said spray nozzle orifice andsaid passageway is arranged to direct the air blast angularly in thegeneral fuel spray direction and across the same.

7. Combustion apparatus as defined in claim 4 wherein said air blastpassageway is constructed and arranged to direct an air blast angularlyin the general fuel spray direction and so as to engage a side of saidconical spray pattern and atomize and deflect at least part of theatomized fuel spray toward said ignition device.

8. Combustion apparatus as defined in claim 4 wherein the air blastpassageway has an input throat and a diverging mouth of largercross-sectional flow area than said throat forming said blast orificeand providing for rapid expansion of air at the orifice and a spreadingof the air blast.

9. Combustion apparatus as defined in claim 4 including means forsupplying air to said air blast means at a pressure to providesubstantially sonic air velocity at the input to said air blastpassageway.

10. Combustion apparatus as defined in claim 9 wherein the air blastpassageway has an input throat and a diverging mouth forming said airblast orifice,

said diverging mouth being formed to provide a critical air pressuredrop therethrough with a change in air pressure to about 0.53 of the airpressure in the input throat and a resultant supersonic air velocity atthe air blast orifice.

1. Combustion apparatus for a gas turbine, comprising a combustion chamber, a liquid fuel spray atomizer nozzle for atomizing liquid fuel sprayed into said combustion chamber, said spray nozzle having a body defining a spraying orifice, said body having fuel passage means for directing the liquid fuel through said orifice in a substantially hollow conical spray pattern at atmospheric pressure, a fuel ignition device, and means for providing an air blast directed at said fuel spray pattern from only one side thereof for atomizing at least a part of the liquid fuel forming said spray pattern and directing at least a part thereof into igniting proximity with said ignition device.
 2. Combustion apparatus as defined in claim 1 wherein said air blast means includes means for controlling the operation thereof.
 3. Combustion apparatus as defined in claim 2 wherein said controlling means is operative to render said air blast means operative during starting ignition of fuel in the combustion chamber and for rendering it otherwise inoperative.
 4. Combustion apparatus as defined in claim 1 wherein said air blast means comprises a member having therein an air passageway with a blast orifice and constructed and arranged to direct an air blast to engage at least a part of said fuel spray pattern and to atomize the same and deflect at least a part of the atomized spray toward said ignition device into igniting proximity therewith.
 5. Combustion apparatus as defined in claim 4 wherein said air blast passageway is constructed and arranged to direct an air blast directly at and across the conical fuel spray pattern toward said ignition device.
 6. Combustion apparatus as defined in claim 4 wherein said air blast passageway orifice is closely adjacent to said spray nozzle orifice and said passageway is arranged to direct the air blast angularly in the general fuel spray direction and across the same.
 7. Combustion apparatus as defined in claim 4 wherein said air blast passageway is constructed and arranged to direct an air blast angularly in the general fuel spray direction and so as to engage a side of said conical spray pattern and atomize and deflect at least part of the atomized fuel spray toward said ignition device.
 8. Combustion apparatus as defined in claim 4 wherein the air blast passageway has an inpuT throat and a diverging mouth of larger cross-sectional flow area than said throat forming said blast orifice and providing for rapid expansion of air at the orifice and a spreading of the air blast.
 9. Combustion apparatus as defined in claim 4 including means for supplying air to said air blast means at a pressure to provide substantially sonic air velocity at the input to said air blast passageway.
 10. Combustion apparatus as defined in claim 9 wherein the air blast passageway has an input throat and a diverging mouth forming said air blast orifice, said diverging mouth being formed to provide a critical air pressure drop therethrough with a change in air pressure to about 0.53 of the air pressure in the input throat and a resultant supersonic air velocity at the air blast orifice. 